1. Field of the Invention
The present invention relates to a measurement instrument connected to an external controlling apparatus such as a personal computer (hereinafter referred to as “PC”).
2. Description of the Related Art
For example, there is a known measurement system which is a connection of a measurement instrument such as a displacement sensor, a temperature sensor and a visible sensor with an external controlling apparatus controlling the measurement instrument, herein, the external controlling apparatus implementing determination based on a measurement result by the measurement instrument (for example, refer to JP2001-141524).
The above type of measurement instrument continuously outputs a measurement value in real time to the controlling apparatus. The controlling apparatus is responsible for receiving the measurement value. In the case that a measurement object moves, timing information about when the measurement instrument acquires the measurement value is important. The controlling apparatus determines this timing information, by using an external synchronizing signal and the like. For example, when a work moving on a line flows to a predetermine position, a synchronizing sensor for sensing the work is turned ON, and synchronously with this ON input, the controlling apparatus acquires the measurement value from the measurement instrument.
In the case that the controlling apparatus is a general-purpose machine such as a PC (Personal Computer) and a PLC (Programmable Logic Controller), however, a connector terminal of the synchronizing sensor is, as the case may be, not provided. In this case, using a serial output of a digital signal such as USB for output of the measurement instrument does not continuously output the measurement value in real time. Therefore, it was difficult for the PC to acquire, in real time and per constant period, the measurement value in combination with the timing information. Thereby, the measurement value and the synchronizing timing were not capable of taking such an action that the synchronizing sensor's output is acquired on the PC side.
With the above conventional problems taken note of, it is therefore an object of the present invention to provide a measurement instrument which is capable of outputting to an external controlling apparatus a measurement value of a measurement object in combination with timing information about when the measurement value is acquired.